


Seaglass

by Laiquilasse



Category: Sherlock (TV)
Genre: Anal Play, Anal Sex, Curiosity, Exploration, Fluff, Friendship, Hand Jobs, M/M, Octopus Sherlock, Sailor John, Scientist John, Tentacle Sex, Tentacles, its pretty obvious where this is going, merman au, sherlock is a curious fish, tentacle jobs?
Language: English
Status: In-Progress
Published: 2017-09-08
Updated: 2018-11-30
Packaged: 2018-12-25 11:14:41
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 4
Words: 7,657
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/12034734
Author URL: https://archiveofourown.org/users/Laiquilasse/pseuds/Laiquilasse
Summary: John ends up in the ocean, and his rescue comes from someone with rather too many limbs and too much curiosity. The two men from different worlds discover and explore one another, and their feelings. No non-con, consenting characters, with gently curious scientific interest. Tentacles plus feelings.





	1. Chapter 1

**Author's Note:**

> Set in the late 1890s, not intended to be even slightly historically or scientifically accurate.

As he swam, John was grateful that the one decent thing his drunken father ever did was teach him to swim. Sure, it wasn't seen as something you needed to know - after all, a half-decent sailor should never end up in the water - but it was serving him well right now.   
The bad weather had sprung up out of nowhere, capsizing his tiny riding boat. John wasn't strong enough to tip it back over - not and stay afloat in the increasingly large waves. He decided to abandon it, and tucked one of the flat oars (thank goodness they floated) under his chest as he kicked away, heading in what he hoped was the direction of the shore.   
A wave rolled him into the air, crashing him down in a haze of painful bubbles. The oar spiralled away, and when John kicked to the surface, he realised he was in trouble.   
Rain had started - salt-water was stinging his eyes and skin, and he really should have stayed with his boat.   
Another wave crashed down, knocking the wind out of John's lungs, and sending him upside down, water fighting to get up his nose and into his ears and mouth as he kicked, not knowing whether or not he was kicking up or down, his lungs hungry for air, eyes seeing nothing but a wall of precious oxygen racing him to the surface.   
It was the last thing John saw before his chest tightened horribly, and he stopped fighting altogether.

*

Sherlock had watched the land-walker as it struggled to right itself. It did alright, the first time, but the second it let out a great gush of air from its mouth - surely that wasn't sensible?   
The walker moved feebly, swimming across instead of up - its limbs were too few and too heavy to really be suitable for the water - before flailing its upper arms, and going still.   
Was it dead?  
A pang of guilt shot through Sherlock's arms. He didn't want the thing to die, not really. They were simple creatures, they didn't really know what they were doing.   
He swam over, and took hold of the walker, squeezing its chest, assuming its vital organs were there.   
There was a pulse, rapid and faint.   
He shoved the limp mass of body up to the surface.   
The cold air shocked the creature, and it thrashed all four of its arms as it gasped down air, choking on it, coughing up something that looked like vile yellow ink - was it trying to repel Sherlock? Sherlock considered inking the thing straight back, then realised the walker was going limp again.   
Fear, then. And exhaustion.   
Well, he could try and deal with that.

*

John couldn't believe the pressure on his chest. It felt as though someone was sitting on it. He groaned, screwing his closed eyes tight as he tried to get away from the sensation, which seemed, if anything, to be moving.   
"What..." he opened his eyes, focussing on... not the sky. Not home, either. A cave..?   
He blinked, and looked down at himself.   
And shrieked in horror at the sight - good god above something was eating him alive - its horrible, evil, tentacled mouth was strewn over John's body, and John was inside it...  
He kicked hard, and tried to scramble away. Pain shot through his limbs, and tore at his skin as he realised he was naked, and the disgusting tentacles were armed with suckers - an octopus? But they never left the water..?   
Did they?

*

Sherlock's instinct to hang onto the struggling creature was stopped short as the thing cried out in pain. Sherlock relaxed the grip of his suckers, and let the walker crawl backwards, quickly away.   
There were circular red marks on his skin where the sucked had bitten down on him. He was fragile, then.   
His body temperature was dropping already.   
Sherlock sat up, and shook his head. "You will die if you get too cold, you primitive idiot."

*

The noise John made was nowhere near a word. It was a nonsensical yell, his brain refusing to accept the logic of a human torso rising from a mass of blue-black tentacles. The face that looked at him was almost alien - the pale eyes overlarge and glaring against the greyish skin, with rope-like dark hair completing the picture.   
And it spoke.   
Or, maybe it did.   
Not in words John could understand, at any rate.   
The beast rolled its eyes. It actually rolled them, as if John was an imbecile. And then it spoke again, pointing at John with a finger, nodded as John began to shiver.   
Had... had it been keeping him warm?  
John frowned, then rubbed his arms carefully, as if warming himself, looking at the creature.   
It didn't seem to understand the gesture, and instead reached for him with four of its tentacles, grabbing him around the arms and waist and dragging him forward.   
"Ow!" John gasped as he topped forward, his bare knees scraping on the rocks, drawing blood. But he had no choice but to let himself be dragged, back into the distinctly slimy, though admittedly warm, embrace, and let those tentacles splay over his body.

*

The walker went quite still once Sherlock covered him again. He hasn't gotten too cold, but until it was dawn and the sun could warm him, he would have to make do. Even if he did look mildly terrified.   
Maybe they were prey animals, the land-walkers. It would explain the skittish behaviour. If only there was some way to ask it.   
Sherlock felt the walker shiver, though apparently not with cold. He sat up and looked down at it, at it's browny-pink skin, tiny blue eyes, and yellow hair. He'd discarded the walker's outer layers as soon as he discovered they were not its skin, but hadn't given much time to properly cataloging it, yet.   
Still.   
There was time, now.   
Sherlock traced an arm over the walker's head, learning the size - about the same as his own - and texture. Its hair was very fine, and starting to dry out. The creature tensed horribly as the tip of Sherlock's arm touched into the shell of its ear - perhaps they were sensitive - so he moved on. The walker's skin was soft, though dry - Sherlock's arm left a visible sheen of slick in its path. The creature stayed still as Sherlock carefully lifted an eyelid, touched the rim of a nostril (the creature pulled a rather amusing face at that), and pulled down its lower lip to see the frankly blunt and unimpressive teeth.   
He brought another arm up, and pushed the jaw open.

*

John made a noise of protest at that - the octopus-man had been quite gentle as it touched him so far, like it was learning, or something - but John wasn't sure he wanted one of those tentacles in his mouth, even if the suckers weren't hurting him anymore.   
The creature ignored him, and ran the tip of a tentacle over his teeth, bottom and top, before prodding his tongue.   
There was no taste whatsoever, which was a relief.   
The tentacle touched again, winding around John's tongue to grip, before inching back down his throat.   
John gagged, and pushed the limbs away. "No. No, I'll be sick. Stop it."  
The creature frowned at him.   
John repeated. "No."  
"No?" it said.   
"No." John folded his arms over his bare chest, trying to look authoritative, though he was flat on the seaweed-covered rock.

*

Sherlock was annoyed. The creature's mouth obviously existed to consume food, and so had a passage down to its stomach. Unless it had a regurgitation reflex.   
He considered the yellow mess the creature had produced. Perhaps that wasn't ink, after all. But what animal would give up undigested food? How utterly wasteful.   
He accepted the refusal, though, and went back to examining the land-walker's throat - it didn't like it when he squeezed - and chest... the creature was of indeterminate sex. Sherlock had seen that it had a penis, and yet it also had nipples for suckling young. He could only assume the creature changed sex depending on the situation. He felt over the creature's nipple, a sucker attaching to one, and making the land-walker gasp.   
Sherlock watched him sharply. It was a different gasp from before - it wasn't in pain, this time. And its face was colouring with blood in some sort of display.   
A warning, perhaps.   
Or... to impress?  
Was it some sort of mating display? That would be interesting, and also worth watching. Sherlock wondered if he could keep this creature here, and maybe capture it a mate, somehow. He mused on this as he continued his exploration of the walker's body, watching as the pinkening skin continued, down the chest.

*

John wanted to shut his eyes when the tentacles got to his groin, but he was worried that if he didn't watch they might do something horrid.   
The slick appendage felt over his cock, pulling gently at the foreskin before going to grip his scrotum and John had to yell "No!" for fear of injury.   
The octopus-man shook his head, and went back to examining John's cock, which was, embarrassingly, reacting to the attention with more enthusiasm than John would have liked.   
A tentacle dipped shallowly to his urethra, making him hiss in distress, before going back to the softer skin at the head, manipulating it back and forth until John let out a soft cry. The suckers felt like deep kisses against his skin, and the motion was just so curious and careful...  
The tentacle wrapped around his hardening cock, and squeezed.

*

The walker gave a sort of moan. Its face was still flushed red, and its penis was hard - it was definitely sexually stimulated. It hadn't used that refusal sound again, so Sherlock moved his arm again, watching the way the outer skin moved over an internal shape rigid with either fluid or blood - he'd guess blood from the flushed red state of the exposed inner tip. He passed the tip of an arm over it, feeling the relative smoothness, tasting the lubricating fluid the creature was producing. A thin strap of flesh prevented the skin being moved back too far, but what was exposed to the air was as tempting and smooth as sea-glass.   
Sherlock passed a finger over it, and the walker moaned again, his fingers clutching at nothing as his hips bucked up. He was redder than ever, and Sherlock felt a moment of worry - did these creatures die once they had released their sperm? - but that quickly gave way to surprise as off-white fluid erupted from the penis, accompanied by the creature's thrusts and soft moans, and the creature covering its face with its hands.

*

John was mortified. He'd actually orgasmed from the creature's attentions. He'd had no control over himself at all. This was appalling. This had to be a dream.   
Hands touched at his arms, pulling them down. The familiar sensation of hands over tentacles grounded him, and he looked up at the creature, which had a look of concern on its face.   
It asked something. John could tell by the way the voice went up at the end.   
"I'm alright," he nodded. "Just... that happens, if you do that."  
The creature looked down at them both, and then back to John's face, before speaking again. It didn't sound cross, at least.   
John sighed. "Where am I? When's dawn?"  
"Dorn?"  
"Dawn," John said. "The sun comes up. You know, the sun?" He motioned with a hand, up high, splaying his fingers like the sun's rays. "In the sky?"  
"Sky," the creature repeated, copying the motion. It said something else, too fast for John to catch.   
John shook his head. "This is getting us nowhere." He patted the chest of the creature with his hand. "Do you have a name? Your name?"  
A frown came as his answer.   
John patted his own bare chest. "John." He touched the creature's, expectantly.   
"Sherlock," came the immediate answer. "John, Sherlock," it pointed from him to itself, and seemed somewhat amused.   
"Nice to meet you, Sherlock," John said. "Wish I'd kind of known your name before you started fiddling with me, mind..." he closed his eyes. "I'll probably wake up in the morning in my own bed."  
Sherlock paused, before lowering himself on top of John again, this time so they were chest to chest, Sherlock's tentacles splayed over John's nakedness, keeping him warm.   
"Please don't molest me in the night," John yawned, before he went to sleep.

 


	2. Chapter 2

John woke the next morning feeling distinctly sore from sleeping on the seaweed-covered rock all night. 

He jumped, the sensation of the tentacles covering him only a mild shock as the memories of the night before came back, making him blush and shift nervously. There was a tentacle wrapped around his arm, another coiled around and through his fingers, and his legs were knotted up with the things. If they chose to move, they could very like rip John in half. And those suckers, although soft and kiss-like for now, had a nasty bite, he knew.

He moved again, testing to see if he could get away without hurting either himself, or Sherlock. It wasn’t exactly an easy task – the one wrapped around his bare thigh tightened up, brushing against the curve of his arse, making John tense slightly. The tentacles hadn’t explored _there_ , last night, at least.

Sherlock looked up as John tried to extract himself. He relaxed his tentacles, letting John wriggle free. He asked something, probably if John was alright. 

"Good morning," John replied. "Um... is it morning? It feels like morning, at least." He eased himself to the side, and Sherlock lifted his tentacles out of the way, watching him intently.

John stretched, rolling his shoulders back, working the crick from his neck. He felt dry, now, and not cold anymore, though he was still nude of course, and, now he thought about it, rather keen to relieve himself. 

Sherlock stretched, too, his tentacles all unfurling, and John could see now there were eight of them - and when stretched they were surprisingly long. At their thickest point, where they met in a web of thick stretchy muscle, they were as round as John’s bicep. The tips were, however, incredible fine. As John watched the arm-like appendages relax out of the stretch, he could see them undulating, changing thickness and size… And John knew they were delicate as well as strong. 

The thought made him shiver. 

"Um..." he glanced at the water lapping at the edge of the rock. He badly needed to piss, but Sherlock lived in the sea. Was that rude? Should he try and hold it in?

Sherlock saved him the worry by half-rolling into the water and sighing, apparently taking the initiative, his lower half out of sight as he leaned lazily on the rock.

John turned his back and emptied his bladder, noticing that he was most definitely dehydrated. Now he thought about it, his mouth tasted quite bad, and he had a bit of a headache forming at the base of his skull. And he hadn't had anything to eat or drink since yesterday afternoon...

"Sherlock," John asked. 

The creature heaved itself out of the water, and looked at him. "John?"

"I... I need to go home. I need to get to shore. The shore?" John looked around the cave as if looking for a clue. "God above, this is frustrating."

Sherlock looked like he was thinking. He held a hand up, and said something firm, before slipping into the water and away from sight, leaving barely a ripple.

John chewed his lip. 

He carefully assessed his options. He was trapped, surrounded by water, on a rock, in a cave, in the ocean... with a half-man, half-octopus. 

Who'd spent some of the night playing with his cock. Until he ejaculated. John’s cock gave a stir of interest at the remembered sensation of those suckers on his erection, the steady back-and-forth working of his skin.

John pinched himself. "Not a dream, then..." He took several deep breaths, willing away the start of the erection he was sporting. It was probably a good thing he didn’t feel well. The last thing he wanted was for Sherlock to come back and see him like that, again.

John shook himself. He needed to try and concentrate – this wasn’t his life, whatever it was. He was twenty-seven years old, unmarried, and only just given his own responsibility in the town's doctors' practice... at least he hadn't drowned. 

There was a surge at the water's edge, and Sherlock reappeared, speaking rapidly, and motioning for John to come closer. 

John walked over, but clearly not fast enough as Sherlock reached with his tentacles and grabbed John quickly around the chest and arms, barely giving him time to gasp a breath before dragging him under the water. 

 

*

 

Sherlock held John close as he propelled them both through the water. He could have spent longer trying to explain, but carrying a weight slowed him down enough as it was. There was a ship close by, and Sherlock needed to get the sailors on board to see John and rescue him - he could never swim that fast in time by himself. Land-walkers might spend plenty of time in the sea, but they didn’t _belong_ in it.

As soon as they were out of the cave tunnels, Sherlock shoved John to the surface. He gasped, trying on impulse to free his arms, splashing and creating so much commotion that there was a shout from the nearby ship. 

“Man overboard!”

There was a splash – they’d thrown a rope to John, who grabbed at it, his arms shaking.

Sherlock let go of him, and was mildly impressed that John could kick enough to stay above the waves. Someone had taught him to swim.

John turned to look at him. "Sh-Sherlock - _thank you_ -"

"...you," Sherlock repeated. He moved away, ready to dive.

Then hesitated.

He reached out, and touched John over the heart, as was custom. "Until we meet again, John." And then vanished beneath the waves, into the dark depths. 

 

*

 

John had to spend a week in bed on his superior's orders. He was, according to Dr Theakston, severely dehydrated and delirious. That made sense, he supposed, as he lay in bed after being sick again. He was being made to drink water and sugar and broth, and his stomach felt awful. He had truly astounding dreams, where he hallucinated his father was still alive, his sister not run away, and his application for the army approved.

He dreamed of the sea, of gunfire, of patients dying on his table, and cadavers rising from the drawers.

He woke every morning drenched in sweat.

Maybe Sherlock hadn't even been real. 

But, as John lay back against the pillows, running a hand over his damp-cooled body, he knew there were some things he couldn't have imagined. He couldn’t have imagined that warmth, helping his stay alive after the ocean’s icy grasp. He couldn’t have imagined that careful, gentle exploration of his body, or the pleasure that the creature had drawn from it. That sucking grip, the steady work of his cock, and the gentle tease of his glans, the tentacle tasting his pre-come even as it lubricated, mixing with the shining slick Sherlock’s tentacle’s produced. John came silently, into his handkerchief, cursing at how easily even the thought seemed to bring him off, now.

John felt better after the week recovering, though his legs were still shaky. He sat at his desk making notes on the cave he'd woken up in, and a few cryptic notes about Sherlock, though was too embarrassed and worried to write down anything concrete. He drew an example of one of Sherlock’s tentacles, and half-heartedly labelled it ‘octopus’, though that was far from the truth.

“I think another week’s recuperation,” Doctor Theakston said, taking John’s temperature that evening. “I don’t need you collapsing whilst dealing with patients.”

“I’m fine,” John said around the thermometer. “I walked the promenade, today.”

“Another week,” his boss said, firmly. “Most people would be glad of the holiday.”

“It’s not a holiday if you’re on bed-rest,” John said, grateful for the removal of the glass rod.

“I never said anything about bed-rest. Go for walks, get your strength up, eat proper meals… Just stay out of the sea.”

John tried not to look guilty – he’d been planning to row out the first chance he got, to try and find that cave, again. “If you insist, sir.”

“I do insist. Not until you’re up to swimming again, at any rate.”

 

*

 

John ignored the advice entirely.

He checked, and double-checked, the weather. And took out a boat belonging to the practice, his own having been lost. He rowed out in the morning, a leather satchel of supplies in the base of the vessel, and carefully plotted his travels in his notebook as he went, a fat compass sitting to hold the pages open.

The cove wasn’t as far as he thought – he came to it after just over an hour’s gentle rowing, and steered himself towards it. A ‘C’ shape of rocks, there was no sign of the cave he’d been taken into, but he knew it was only accessible via the water. There was, however, a crest of rock at sea-level, so John headed for it.

“John?”

John almost let go of the oars in his fright, as a pale-grey face and arms appeared, hanging off the port-side of the rowing boat. “Good god, man… You gave me a fright…” he swallowed. “Sherlock.”

The ocean-dweller smiled, and looked him over approvingly, then with curiosity at his things.

“I’m going to tie off,” John pointed at the rocks.

Sherlock nodded, and swam to the back of the boat, grabbing the loops of rope there, and pulling hard, dragging John and his boat effortlessly through the water to a collection of stalagmites. They made ideal points for a knot of rope, and John quickly hitched up the boat, before collecting his things and standing.

“Ah,” he mused. “I may have to swim – what –”

Firm tentacles grabbed him around the middle, picked him up out of the boat, and deposited him on the rock with only a few water-stains on his clothes.

“Oh,” John smiled. “Thank you.”

Sherlock heaved himself out of the water, pausing to let the rivulets of moisture run down his body. John noticed the sea-person had a strong musculature – he hadn’t seen that in the dimness of the cave – and his tentacles were quite capable of pushing his weight from the water, though were not firm enough to act as transport once out of it – Sherlock had to crawl. And his skin was clearly tougher than John’s, as the rocks left no marks where they bit into it. John’s knees were still sore from their rough treatment over the stone.

Sherlock crawled right over, and into John’s personal space, his tentacles splaying over John’s lap as he put a hand on John’s chest, just as he had when they parted.

John raised his own hand, and copied the motion, feeling a bit silly, but his hand on Sherlock’s chest made the creature shudder, and his tentacles darken, just for an instant.

Was he blushing? Was that a blush?

“Um…” John licked his lips apart as Sherlock watched him intently. “Are – are we friends? Is… is that what this is?”

Sherlock looked away, clearly taking no notice, and started opening the catch on John’s bag, and looking inside.

“Alright,” John frowned, watching the dextrous tentacles lift out bits and pieces, and eventually his notebook. “Don’t get that wet,” John took it, quickly. “It’s paper. Look…” he flipped a few pages, and turned it around when he reached the portrait he’d drawn that morning. “It’s supposed to be you, but… I don’t know. I’m not an artist.”

Sherlock stared at the paper, his eyes wide, lips parted slightly.

He reached out, and touched the drawing with gentle fingers.

 


	3. Chapter 3

It was like an engraving, only flat. It was etched, somehow, onto the thinnest slice of wood, and the image was of Sherlock. Sherlock had seen his reflection before, in polished surfaces, or in mirrors salvaged from sunken ships, but not like this. This was Sherlock, as John saw him.

Sherlock traced the coil of his illustrated arms with a finger, taking in how John had captured his body, the shape of him, the dark curls of his hair. It was… it made him feel very strange, inside.

“How did you do this?” Sherlock asked.

John must have picked up on the tone, because he turned to a blank page, and picked up a yellow stick, and rubbed the pointy end on the paper. It left a dark grey mark.

“It’s a pencil,” John said.

“Pencil,” Sherlock repeated, curling a thin arm-tip around the stick, and lifting it, trying to press it to the paper, and struggling with the motion.

John took it from him, and pressed it into his hand, instead. “Try that,” he said, manipulating Sherlock’s fingers around the stick. It didn’t feel comfortable, but John seemed satisfied with it as Sherlock went to make a mark on the page.

He drew a wobbly line, and frowned at it.

John said something, but Sherlock adjusted his grip, and did it again, this time drawing a circle, or a squashed-version of one at least, another line, and another.

“You’re getting it,” John said, which sounded like praise. He asked for the pencil, and Sherlock handed it over. John turned to another clean page, and wrote several definite, large marks, before turning the page for Sherlock to see.

It didn’t follow a pattern, but looked intricate and pleasing, and Sherlock was about to nod at the land-walker’s efforts when John pointed to the marks, everything changed.

“John,” he said, pointing to the line of marks at the top. And then: “Sherlock,” he ran his finger under those at the bottom.

Something exploded in Sherlock’s mind. He stared at the marks, noticing how each one was different – how the two _names_ were different.

“John, Sherlock,” John repeated, saying them slowly as he drew his finger under the names.

Sherlock pointed. “John,” he said. “…Sherlock.”

“Yes,” John beamed, and said something else, but Sherlock could barely even hear the sounds. He reached out, and traced the shapes that made up his name until they smudged until his damp finger.

“Here,” John gave him the pencil again. “Try to write it?”

Sherlock instantly understood what was expected of him, and concentrated hard to try and copy the marks. He struggled with the ‘S’, and the ‘e’, but the other letters came well enough, and though his effort was wobbly and large, it clearly said ‘Shэrlock’.

“Sherlock, that’s amazing,” John said, looking at the marks. His face was lit up, and he was baring his teeth, but it wasn’t menacing, it was in happiness.

“What is this?” Sherlock asked, holding the pencil up. He looked from it to the paper in wonder.

His people were oral history-keepers. One member of the tribe was expected to remember all their records and stories, and to pass them on with regular re-tellings. But this… with this you could write down anything, and look back on it as much or as often as you liked. You could learn so much more, and even forget it, because you could always look back at the papers…

Sherlock’s head suddenly hurt, and he handed the pencil back to John as he pressed his temples. The implications of this were too much.

 

*

 

John watched Sherlock wince in apparent discomfort. He looked at the paper, and felt sad. Sherlock couldn’t take this into the ocean with him – it would dissolve beneath the sea, into nothing. But Sherlock was intelligent – he could copy the letters, and he understood that said his name, John was sure of it.

He reached out, and touched Sherlock’s warm, but clammy, shoulder, in sympathy.

Sherlock leaned into the touch, before turning, and saying something, pointing at the paper.

John took a guess. “More? More words?” he held the pencil up.

Sherlock nodded.

“Which words?”

Sherlock considered. Then said something, pointing to the water.

“Ocean,” John said, writing it clearly. And then ‘rock’, ‘sky’, ‘boat’, ‘day’, ‘night’… words as Sherlock acted and said and demonstrated what he wanted, delighted each time John named the thing, and wrote down the name. His heart swelled every time Sherlock grew more and more delighted, his handsome face making John remember their first night on the rocks, and not knowing quite how to process the feelings that came with it.

Then Sherlock pointed at him.

“John?” John offered.

Sherlock shook his head. “No,” he said, in English. “You,” he added. “John…”

“Hmm…” John quickly sketched out a group of people, all standing on their legs together. “Humans?” he showed Sherlock the picture.

“Humans,” Sherlock repeated. “John… is human.”

“And Sherlock is..?” John smiled, wanting to hear the word Sherlock used for his people.

“Sireno,” Sherlock said. “Mother… Sirena. Sirens.”

John smiled. “Sireno,” he repeated.

“Human, and Sireno…” Sherlock said, reaching out, and John thought he was looking to take the pencil again, but Sherlock’s tentacles too hold of the stationary, and put them back into John’s bag as his hands touched at John’s face, his throat, his chest.

 

*

 

The land-walker – the _human_ – sighed as Sherlock touched over him. He felt hot, John did, warm and soft and dry, and Sherlock wanted to smother him.

He wrapped his arms around John’s chest and arms, and pulled him close, so they were tangled together, John’s legs – they were legs on his lower half, apparently – were wrapped around Sherlock’s waist, Sherlock’s arms holding him up as they ended up face to face.

Then, John did a strange thing.

He leaned forward, and pressed his mouth against Sherlock’s.

Sherlock’s eyes went wide in confusion, and he stayed still as John drew back, a look of disappointment on his face.

“No kiss?” he asked.

“Kiss?” Sherlock frowned. “Kiss…” he went forward to copy the motion, and pressed his mouth against John’s, firmly. Perhaps it was like the chest-touch of his own people. He blinked, as he moved his face away. “Kiss?”

John looked as though he was amused. “Kiss,” he said again, this time bringing his hands up to gently cup Sherlock’s face, his thumbs brushing Sherlock’s jaw before their lips touched again, only this time John was moving his mouth, just enough, just a little for the _kiss_ to feel like a soft massage, that had Sherlock searching for more, copying the motion as John pressed their chests together, his legs squeezing just a little at Sherlock’s pelvis as their kiss continued.

Sherlock wound his arms around John’s thighs, his stomach, around his arms, trying to coil around all of him that he could reach, running softly-touching suckers over his clothes, lifting the fabric out of the way to slip beneath and run up his back, coiling around his throat in a way that had the human gasping in apparent fear for his breath, but he needn’t have feared.

Sherlock had no plans to murder him.

John resumed the _kiss_ , his body tense until Sherlock’s hands touched at his chest, trying to reassure him. It was clear now to the siren that John’s kissing was part of a mating display, though he hadn’t initiated it when Sherlock had worked his seed from him before – perhaps this only happened when the human initiated the contact. Or perhaps the last time had been out of John’s control. That felt rather worrying, though it clearly hadn’t put John off, as his penis was hard again, and pressing at Sherlock’s body through the human’s clothes.

Sherlock unwound his arms from John’s legs, and looked at the fastenings of his trousers. He’d torn them off, before, but that didn’t seem necessary, now. He unhooked the fastening, and pushed the buttons through the holes, making a mental note to ask John how they worked later, before lifting John off his lap, making him cry out in surprise before pulling off the trousers altogether, along with a tighter pair he had on beneath, before re-seating him in his legs, bare legs now wrapped around his waist.

 

*

 

John felt incredibly exposed, with his legs wide apart around Sherlock’s middle. His cock was hard, and Sherlock was already coiling a tentacle-tip around it, stroking softly at the retracting foreskin. But his arse cheeks were spread apart, and he was incredibly conscious of the fact Sherlock’s tentacle arms were wrapping around his legs, exploring the feel of his skin, and edging close to –

John gasped, as an unexpected touch brushed over his entrance.

 

*

 

Sherlock looked at John’s face in surprise. He thought the human was entirely male, but he had an entrance – albeit tight-furled and closed. Sherlock touched at it firmly, the slick of his arm transferring to the taut skin, and probing gently as John shuddered, and hid his face in the crook of Sherlock’s neck, even as Sherlock squeezed at his erect penis.

The dual sensations seemed to be overwhelming the human.

And Sherlock found his own arousal was building because of it.

 

*

 

John thought he might die of embarrassment – he’d put a finger inside himself in the past, who hadn’t? – but this was different. Sherlock was keeping him still, keeping his cock hard, and seeking entrance to his arse. And he was finding it difficult to think of why this might be a bad idea.

Sherlock kissed him again, and John concentrated on kissing back even as the very tip of the tentacle breached him. Lubricating slick came with it, taking the edge off the burn as the tentacle widened, enough to make John gasp and tense.

Sherlock went still, but the tentacle inside John flexed, feeling at his insides, transferring slick to his soft skin, making it difficult to concentrate even as the slender tip brushed over his prostate, just once, but it was enough to make John bite his lip.

“Yes,” he nodded, against Sherlock’s skin, and Sherlock responded by withdrawing his tentacle entirely, before replacing it with another, and John realised with a jolt that this was Sherlock’s hectocotylus – essentially, he was mating with John, not simply playing with him.

“Oh, fuck,” John moaned, gripping Sherlock’s shoulders hard as the thicker tentacle pressed inside him. He forced himself to bear down, to take it inside, but Sherlock was kind – he kept his tentacle slender as it pushed inside – deeper than John thought possible – then making the intrusion swell, gradually, stretching John’s insides out as the soft suckers roamed, playing gently with his delicate insides, rubbing over his prostate and making him moan again. “Sherlock…”

“John,” Sherlock said back, moving his tentacle firmly over John’s cock, starting up a steady rhythm that was soon joined by the thrusts of his hectocotylus – swelling and pushing inside John.

John wasn’t even holding up his own weight – Sherlock had him suspended, being worked and fucked in equal measure, the tentacle around his throat gripping tight, the tip teasing at his mouth. John sucked it in like it was candy, and Sherlock let out a feral cry of pleasure, rolling his tentacle inside John in return, working his cock harder, faster, until John was shaking, trying to hold off but failing utterly. The tentacle inside him swelled further, the ache in his arse doubling as Sherlock fucked him so deep he saw stars. The thick appendage curled inside him, and John came undone.

He cried out loud as he came, spilling over Sherlock’s check and tentacles as Sherlock’s skin darkened for a moment, the colour bleeding out to his tentacles, and the one buried inside John stiffened, and a hot feeling filled his insides as Sherlock came inside him.

It seemed to go on for a long time, Sherlock thrusting continually as he filled John with his seed, the stuff running out of the human eventually, and Sherlock having to lower him down, and put a kiss on his mouth again.

“Oh god,” John said, wincing as a rush of come exited him as Sherlock withdrew his hectocotylus. “Oh god, Sherlock…”

“My John,” Sherlock said, his deep voice like a purr. He wrapped his arms – his human-like arms – around John’s chest and held his tight as he kissed his neck. “My John.”


	4. Chapter 4

**Notes for the Chapter:**

> More than a year later, and I finally add another chapter. Wow, guys, I suck. Enjoy!

Sherlock watched John row away, his little boat moving steadily on the small waves. He felt strange to be alone, after their mating. His kind did not mate for life as a rule, and Sherlock had scoffed at any talk of rising emotional responses and dependency that might arise after a mating. Certainly he had never experienced it, before.

Except for now…

Was it because John was so alien? Or because he was something else? Because he had shown Sherlock those words? The sensation that had welled within Sherlock at seeing the writing had had nothing to do with lust, but it had been a very deep _want_. His lust for the land-walker had seemed like the only way he could express it.

He needed to tell someone.

Not about the mating, though they would already know that had happened – the pale flush of his arms was a giveaway.

No, he needed to tell them about the marks on the “paper”. The words.

He needed them to understand.

 

*

 

John took a bath when he got home. His backside felt out of sorts, though not in pain. There was also a sheen of slick over his legs, and salt from the water in his hair. He rinsed himself clean before getting into the tub to soak, relishing the warm water.

He wondered if he ought to feel guilt for what had happened. Perhaps someone else would feel sinful, or dirty.

He just felt lonely.

John wasn’t a romantic – he knew that sexual activity didn’t equal love, or even real affection. But he did for Sherlock. The mer-man, if that’s what he was, was intelligent and gentle, and perhaps in another world, they would have been friends.

He dried and dressed himself, and got into bed. His exhaustion washed over him as soon as he lay back.

His dreams were of the sea.

 

*

 

“Markings?” Mycroft asked. He indicated the carved walls of his chambers. “That is nothing unusual, brother.”

“This was not merely images, brother,” Sherlock said, trying to hold onto his patience. “This wasn’t a story-picture, or a portrait. This was… words. Individual words, given a shape. Each sound in the word given a symbol. A tiny one, so many words could be recorded together.”

Mycroft frowned, as he tried to understand. His deep red arms gripped the edges of the stone he rested on. “Could you replicate it?”

“I..” Sherlock dragged the tip of one of his arms through the silt floor. It stirred up, and clouded in the water. “If you came to the surface, I could show you.”

“Then what good is it?” Mycroft rolled his eyes. “We do not dwell on the surface for long, Sherlock…” his eyes narrowed. “You said a land-walked showed you these things? How? They are unintelligent beasts.”

“We have misjudged them,” Sherlock said, aware of his brother looking over his clearly recently-mated body. He ignored the look, as much as he could. “They have language, Mycroft. They talk. They… can learn. They make things. On the land… I suspect they could even have primitive technology.”

Mycroft looked back at his brother’s face. “You are… acquainted with one, yes?”

“Yes.”

Mycroft looked torn. “Beings they might be, Sherlock, but if your condition is related to this… meeting…”

“He consented,” Sherlock said softly.

Mycroft looked wretched. He pushed himself off the rock, and swam over. “Sherlock. He is not our kind. You understand how this would be seen by our people?”

“But not by you?”

“I have long since given up trying to understand you. But keep this to yourself, Sherlock. People will think you sick.” He shook his head. “As for these markings… can you bring some of this – this ‘paper’, down to me?”

“No, it doesn’t survive in the water,” Sherlock said.

“Then, I really have to wonder what use it is, Sherlock.”

“You don’t understand. You would if you saw it. Come with me, to the surface.”

“You know the leader of our tribe does not surface. Neither should you, as my brother.”

“This is more important than tradition!”

“Sherlock,” Mycroft snapped. “You are obviously infatuated. With this land-walker, and with these markings. “You must remain here, now. Rid your mind of these obsessions. They will get you nowhere.”

Sherlock was silent for a moment.

“You will forget about it,” Mycroft said.

Sherlock looked up. “I don’t have to remain here.”

“I would prefer it if you did. The surface is no place for a prince.”

“I mean… I do not have to remain a prince. I do not have to remain in the water.”

Mycroft’s expression moved from caring to shocked to outraged in a matter of seconds. “You… you would dare…”

“To learn? You know I would.”

“Sherlock… there has not been such an incident for – for decades!”

“About time there was another, then.”

“If you left,” Mycroft said, “…you could never return. You understand that? You would be giving up your history, your people, your family, for… what?”

Sherlock turned away. “For a future, Mycroft. There is nothing here that I want.”

Mycroft stared at him. “Is that what you truly think?”

Sherlock didn’t answer, just swam for the archway back out into the ocean, his chest feeling tight, and his arms tight with worry.

 

*

 

John spent the next few days making something for Sherlock.

He knew there was no way for paper to survive the ocean, but if Sherlock wanted to continue to learn to speak English, and to write, he needed more than John’s yellowing notebook.

John collected a few old schoolbooks from the second-hand shop in the town, and spent his time cutting relevant pictures and words from them. The books had been used, but only in pencil, and the marks were easily rubbed out or cut around.

John ended up with a book full of pictures of things he thought Sherlock would recognise. Crabs, fish, boats, sand, the sun, sky… and some things he wasn’t sure about, like pens, land-animals, birds, and clothing. There was the name of the object clearly printed beneath, and space for the word to be copied, below that. It was the sort of thing you would give to a small child just starting school. John felt slightly odd about it – Sherlock wasn’t a child, but he needed the basics before he could move onto anything else.

 _How long are you going to keep this up, John?_ An inner voice nagged at him. _He lives in the sea. No matter what you’ve been through together, this cannot go on forever._

John put the book in his waxed satchel, and made a final check of the tides. If he left now, he would have to come back home just as the tide was going out. Not ideal, especially with his still-tired arms and legs.

He could wait another few days.

Except… would Sherlock think he had gone forever? Had he already missed him?

No. Surely not. No one would miss John, even if they had been… intimate.

John shuddered at the memory, his cock stirring as his mind recalled the firm, slick tentacles touching his naked skin. The feeling of being penetrated by that gentle touch, dampened to make it easy, coiling inside him…

John gripped the windowsill in both hands. His cock was hard, and an ache was building already in his pelvis. He pressed a hand to his cock, and ground against the pressure, imagining the soft kiss of suckers on his erection, the hard grip that refused to let him go, that took away his choice of when, or if, to release. His arms, tightly bound in Sherlock’s tentacles, keeping him immobile, a toy to be fucked and worked, his mouth and arse penetrated by one creature, reaching inside him, drawing out pleasure…

“Fuck…” John undid the buttons and fastenings at the top of his trousers, and shoved his hand down inside. He took hold of his erection and gripped hard, gasping at the shock of pleasure than ran through his body. Just remembering what had happened had sent him so close to the edge. Checking the door behind him was locked, he sat on the edge of his bed and freed his cock. He didn’t savour the self-manipulation, just took himself in hand, thumb moving in circles to rub his retracting foreskin over the head of his cock, slick and leaking from pre-come.

John closed his eyes as he moved his hand as slowly as he dared. He recalled Sherlock’s warm hands on his legs, on his arse, on his stomach, pressing against his pulse, the moment of his skin. Sherlock’s uncertain kisses as he learnt how they were done, yet his surety of pressing a tentacle into John’s mouth, coiling around his tongue, another around his throat, making him light-headed. The strength of Sherlock held him still, that thick hectocotylus thrusting inside his arse, stretching his passing, moving in and out of him with slick determination. Suckers caressed John’s prostate, his sensitive insides as the tentacle reached still further inside him… so far that John knew it was purely his imagination rather than a true retelling in his mind, now. But the thought of it made him shudder again, thrusting up into his hand as his wrist moved faster…

“Oh god - !” John hunched over, coming into his own hand, cursing as he did so, working his cock even as he came until he become over-sensitive and had to stop.

He washed off at the basin, before throwing himself onto the bed.

What was happening to him?


End file.
